Dyskinesias (Paroxysmal)

Etiology of Secondary Paroxysmal Dyskinesias

Symptomatic PKD is most commonly associated with head injury or multiple sclerosis (MS). MS is a progressive disease of the central nervous system characterized by loss of myelin, the fatty substance that forms a protective sheath around certain long nerve fibers. Myelin serves as an electrical insulator, thereby enabling the effective transmission of nerve signals. Associated symptoms may include lack of coordination, abnormal reflexes, muscle weakness, paresthesias, as well as visual and speech disturbances.

Symptomatic PKD may also be associated with idiopathic hypoparathyroidism, a condition characterized by decreased activity of the parathyroid glands, an unusually low level of calcium in the blood (hypocalcemia), and abnormal calcium deposits or calcifications in the basal ganglia. Symptomatic PKD may also occur in association with abnormalities of brain structure or function due to insufficient oxygen supply to tissues shortly before, during, or after birth (perinatal hypoxic encephalopathy). Cases are also described in the medical literature in which symptomatic PKD resulted from localized brain tissue loss or necrosis due to a temporary interruption of the blood supply to certain regions of the brain (cerebral infarction, e.g., thalamic, putamenal, or cortical infarct). Other underlying causes have also been implicated (e.g., diabetes mellitus, infantile hemiplegia).

Symptomatic PNKD is most frequently associated with MS or perinatal encephalopathy, but psychogenic etiology is also relatively common. Other causes include hypoparathyroidism, hyperthyroidism, and diabetes mellitus. Symptomatic PNKD may also occur in association with traumatic brain injury, inflammation of the brain (encephalitis), calcium deposits in the basal ganglia, lack of oxygen supply to brain tissues (anoxia), brief interruptions of blood supply to part of the brain (transient ischemic attacks), brain tumors, and or other underlying disorders or conditions. Symptomatic PNKD may also develop in individuals with acquired immunodeficiency syndrome (AIDS).

One case of secondary (symptomatic) paroxysmal exertion-induced dyskinesia (PED) has been reported following trauma as in neck, arm, and shoulder strain sustained during a car accident. In addition, 3 cases of symptomatic PHD have been described, 1 that resulted from head injury and 2 that were attributed to MS.